Hi flower, I'd say the most important thing you could do straight away is stop beating yourself up about any little lapses. It happens to the best of us, after all this diet is a huge thing and totally changes your life, way of thinking and way of dealing with issues in our life. We've given up our support crutch and we really are just learning in my opinion. It's like learning to ride a bike, you just have to stick a plaster on those grazed knees and get right back on again.
Think about the huge achievement you've acomplished. 3 stone in 13 weeks is an amazing weight loss and you should be so proud of that. You'll get that last 2 stone off in no time, so as the others have said just keep thinking why you joined in the first place and that in a relatively short time. You will be able to eat a huge variety of delicious foods, without feeling guilty and while wearing gorgeous clothes! I really do wish you all the best and keep going. You'll look back at this time so positively in the end cos you will have learned from it! x